Pipe joints comprising a sealing ring which is radially compressed to form a seal between a spigot and a sleeve or socket are well known in the art. An example of such a joint, incorporated into a pipe coupling, is discussed in Patent Specification GB 2156466. The joint disclosed therein has an O-ring seal which is seated in the flange of a sleeve, and contacts a spigot which is inserted into the sleeve. An axially movable ring surrounding the end of the sleeve compresses the O-ring against the flange and causes the O-ring radially to deform. The radial deformation forms a seal between the sleeve and the spigot. Joints utilising sealing mechanisms such as this are limited, however, by their tolerance of a variation in the outside diameter of the spigot which is received by the sleeve. Conventional joints are designed to accommodate only pipes which are manufactured to standard tolerances, and are unsuitable for jointing pipes which are constructed from different materials and consequently may have incompatible spigot diameters.
The problem is to design a joint which enables spigots of different materials and different diameters to be jointed and thereby eliminates the necessity for a variety of joints, couplings and fittings, each of which is dedicated toward a specific material and a specific diameter of piping.